<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<meta name="viewport" content="width=device-width,initial-scale=1.0">
		<title></title>
		<style type="text/css">
			body{
				background: #000000;
			}
			.a{
				text-decoration: none;
				position: absolute;
				font-size: 24px;
				background:linear-gradient(90deg, #652364,#798426,#e362f1,#36eff8);
				background-size: 400%;
				width: 400px;
				height: 100px;
				line-height: 100px;
				color: #ffffff;
				text-align: center;
				border-radius: 50px;
				z-index:1;
			}
			a::before{
				content: "";
				position: absolute;
				left: -5px;
				right: -5px;
				top: -5px;
				bottom: -5px;
				background:linear-gradient(90deg, #00aaff,#00ff00,#0000ff,#ffaa00);
				background-size: 400%;
				border-radius: 50px;
				filter: blur(20px);
				z-index: -1;
			}
			a:hover{
				animation: dong 8s infinite;
			}
			 
			@keyframes dong{
				100%{
					background-position: -400% 0;
				}
			}
			a:hover::before{
				animation: dong 8s infinite;
			}
		</style>
	</head>
	<a href="http://kotan.gitee.io" class="a">自动变色</a>
	<body>
	</body>
</html>